Carburetor



Feb. 20, 1934.

G. F. BR UT CARBURETOR Filed June 24. 1929 2 Sheets-Sheet l G. F. BRUT Feb. 20, 1934.

CARBURETOR Filed June 24, 1929 2 Sheets-Sheet 2 f -ald/ f f ng (//l Patented Feb. 20, 1934 UNITED STATES PATENT OFFICE Application June 24, 1929, Serial No. 373,282, and in France June 30, 1928 12 Claims.

This invention relates to carburetors and proposes the construction of a carburetor in which, as the demand for more mixture on the part of the engine increases, the velocity of the carbureted mixture moving toward the manifold increases, so that the maximum weight of the explosive mixture is admitted to the engine at all engine speeds. This provision has the effect of preventing the lag in the operation of the engine which ordinarily occurs when the throttle valve is suddently opened and which is caused by the carburetor being unable to supply at the proper velocity the mixture necessary to satisfy the vacuum with which the carburetor is confronted.

One of the specific objects of the invention is to provide a carburetor in which during the period of transition of the throttle valve from idling to normal running positions, the mixture is produced by a cascade of venturis or similar emulsifying devices, normally submerged, and therefore inactive at idling speeds of the engine, and being uncovered progressively upon the lowering of the level of the liquid fuel which submerges them whereby the venturis come into action in numbers proportionate to the degree of vacuum attendant upon the changing position of the throttle valveduring said transition period, the velocity of the mixture being multiplied in ratio to the number of venturis in action at a time.

Another object of the invention is to provide for taking at least a part of the air used in composing the mixture, from the space above the level of the liquid fuel in the float chamber, the latter communicating with the atmosphere by way of an orifice of a determined and restricted size, whereby sub-atmospheric pressure is maintained above the body of the liquid in the float chamber; and to provide an orifice of a determined caliber below the liquid level in the fioat chamber through which the liquid fuel feeds to the emulsiiiers, the eifect of the Vacuum in the float chamber being to hold back somewhat the body of liquid fuel from freely discharging through the submerged orice, thus permitting the employment of the submerged orifice of larger diameter than would ordinarily be required, the advantage being that the larger orice is not so apt to become clogged or stopped up and that there is less skin friction between the liquid and the walls of the orifice so that the liquid discharges more freely responsive to a sudden impulse or pull on the carburetor, while, on the other hand, an economical supply of fuel to the emulsiiiers is assured at uniform engine speed by the retardative effect of the float chamber vacuum.

A further object of the invention is to provide for counter-balancing the effect of the varying value of the vacuum in the float chamber by providing for compensating proportionate variations in the static pressure or head of liquid resting upon the submerged orice on the opposite side thereof from the iioat chamber.

Other objects of the invention will appear as the following description of the preferred embodiment thereof proceeds.

In the drawings in which similar characters of reference designate like parts in the several views;

Fig. 1 is a vertical section through the car# buretor, on the line 1, 1 of Fig. 3.

Fig. 2 is a horizontal section on line 2 2 of Fig. 1 of the mixture chamber of the carburetor.

Fig. 3 is a cross section taken along the line 3-3 of Fig. l.

Fig. 4 is a cross section taken along the line 4-4 of Fig. 1.

Fig. 5 is a vertical section showing a modied form of the emulsifying unit of the carburetor, while Fig. 6 is a cross section taken along the line 6 6 of Fig. 5, on the line 1, 1 of Fig. 3.

In the following description, the word Venturi has been used in its usual meaning, that is of a passage having a tapered restricted portion therein. In order to avoid any misunderstanding, it should be noted that, by inlet end, in the following description and claims, I refer to that part through which the fluid is admitted axially into the venturi, said portion being either conical or cylindrical, while Icall diverging portion the part that widens out after .the restricted portion.

Referring now in detail to the several figures and first adverting to that form of the invention illustrated in Figs. l and 2, the number 1 represents in general, the carburetor body having -a part constituting a float chamber 2 and being formed with a generally cylindrical and preferably vertical bore 3 which is in permanent com,- munication with the float chamber by way of a passage 4. Above the bore 3 is an intersecting and preferably horizontal passage 5 forming -a mixture chamber and being adapted to commu.- nicate with the manifold of the engine in connection with which the carburetor may be employed. As is seen in Fig. 2, the throttle valve 6 operates in this mixture chamber.

The carburetor is provided with an idling Well '7 into which dips an idling nozzle comprising concentrically spaced tubes 8 and 9. The innerl tube S communicates with the mixture passage by means of the conduits 1l and 12 which enter the mixture passage on opposite sides of the throttle valve. That part of the tube 9 which is below the liquid level of the noat chamber communica-tes with the liquid fuel by means of a passage 13 and it is also formed with a tapering slot 14 placing it into communication with the space between the tubes. Normally when the engine is not running the liquid stands at the saine level in both tubes of the idling nozzle as in the float chamber. The outer tube 8 of the idling nozzle communicates with the mixture chamber by means of an air inlet 15 which opens into the mixture chamber on the carburetor side of the throttle valve. The iicw of fuel from the idling nozzle may be permanently adjusted by a set screw 16. The construction of the idling nozzle does not dier materially from known oonstruotions.

Within the vertical bore 3 is the emulsifying unit comprising a series or cascade of venturis or similar emulsifying devices. This unit comprises a plug 17 screwed into the wall of the vertical bore having a bushing 18 screwed into its lower end, said bushing being formed with a iixed oriflee 19 and the plug and bushing forming above said orice a chamber 2i). In the original assembling of the carburetor, to suit the engine with which it is used, the bushing 18 may be exchanged for another having an orifice of appropriate diameter.

Above the plug 17 is the drum 21, the specific construction and utility of which will be presently described, and above this drum is the final diffuser 22 having an annular shoulder abutting against a shoulder formed on the walls of the tubular bore. The plug 17 is screwed tightly into position against the drum 2i, the latter holding the diffuser 22 firmly in place against the last named shoulder.

The diffuser 22 is formed at its upper end with a divergent passage 23 which cooperates with a coaxial downwardly liaring passage 24 formed in the drum 21. These two passages form anY intermediate constriction and constitute the rst or uppermost venturi. The passage 24 communicates by way of the lateral passage 25, the vertical passage 26, and the side passage 27 with the space within the float chamber above the level of liquid in the float chamber and the float chamber above said liquid level is in communication by way of the passage 28 and orince 29 with the atmosphere. It will be understood that at the time the engine is started and whilesoever it is running solely at idling speed, the diifuser 22 is submerged up to the point at which it does not function as a venturi. The constricted portion of the venturi constituted by the passages 23 and 24 is in communication with an annular chamber 30 the same being in communication with the outer ends of the upper trunconic passages 31 of a rose or annular group of venturis, the lower ends of which are constituted by passages 32 formed in the upper face of the plug 17 coaxial with the corresponding trunconic passages 31 and communicating at their lower ends with a chamber 34 which surrounds the drum 21 and the upper part of the plug 17. At the constricted Y portions formed between the trunconic passages 31 and the lower passages 32, the said venturis of said annular group communicate with a chamber 35, the latter in turn communicating with the central portions of the vaporizing venturis 36.

Said latter venturis open at the top by way of the passages 37 with the passage 24 in the first named venturi and at the bottom they open intoy the chamber 20. A bleed passage 38 leads direct from the chamber 20 to the chamber 34. The vaporizing venturis are formed in their upper part by washers 39 which intersect the plane of separation between the plug 17 and the drum 21 and prevent relative rotation of these members, said washers are provided with a series of apertures 40 establishing communication be tween the vapo-rizing venturis and the chamber 35. The elements above enumerated are those which are essential to the operation of the carburetor according to the present invention. Other features may be observed from the drawings, such as the passage 41 in the lower part of the bushing 18, the purpose of which is toy provide a vent for air which would be trapped between the bushing and the walls of the vertical bore 3, in the initial filling of the carburetor. There is also found the passage 42 having for its object the venting of the central part of the chamber 35 so as to avoid the retention of an inert quantity of liquid fuel in the central part of said chamber. There are also noted the passages 43 and 44 which prevent the condensation of any liquid upon the surface of the passage 23 in the diifuser 22. These elements while not essential have been found in practice to improve the operation and utility of the carburetor.

Having now described the structural details of the preferred embodiment of the invention its theory and method of operation will be described.

It will be understood that all that is hereinafter narrated relative to the sequence of its operative functions, takes place in that very short interval of time during which the throttle valve is opened from that position in which only the idling jet is in operation to that position in which the idling jet is closed and the so-called high speed features of the carburetor are brought into play. In the ordinary carburetor, this transition is accomplished by a decided and progressively increasing vacuum value at the nozzle of the carburetor which the latter is unable to feed with suflicient mixture to produce the proper combustion in the engine on account of the inertia of the mixture, and the fact that suflicient velocity cannot be acquired in the brief interval of the said transition period, to supply the engine With the maximum Weight of fuel mixture upon which satisfactory operation then depends. In consequence if the throttle be suddenly opened from idling to full running position in ordinary engines there is a starvation of the motor with a consequent lag in the operation of the engine sometimes resulting in the stalling of the same and in nearly all instances impairing the liveliness of its pick-up i In the present invention, the operation of the carburetor during this transition period may be divided into four phases.

The rst phase will now be considered in which the liquid level in the carburetor is as indicated by the broken line 5G-50. It will be noted that all of the venturis are submerged and that the liquid fuel stands well up in the idling nozzle.

When the engine is rst started with the throttle valve in the position shown in Fig. 2, only slight depression exists in the mixture passage 5 over the mouth of the diiuser 22, only enough to cause a very slight rise in the level of the liquid fuel which stands in the diffuser. At this time, however, a higher degree of vacuum exists on the opposite side of the throttle valve, drawto the engine.

ing upon the conduit 11, causing a rise of liquid fuel in the tube 9 which is fed direct to the manifold by way of the conduit 11, the air for carbureting this raw fuel being at the same time drawn in through the conduit 12. The rise of liquid in the idling nozzle at this time is permitted through the fact that the liquid fuel in the idling well is under atmospheric pressure communicated by way of the orifice 29, the upper part of the float chamber, and the passage 27 as well as by the passage 15 which stands only a very little below atmospheric pressure.

The second phase in the sequence of functions occurs when the throttle valve has been slightly opened increasing the depression above the mouth of the diffuser 23. As the liquid fuel rises in the diffuser it is correspondingly depressed in the passage 25 which is in direct communication with the diifuser by way of the passage 25. As the depression increases the level of the liquid finally sinks below the upper edge of the passage 25 so that at once atmospheric communication is established throughout passages 24 and 23 by way of the orifice 29, upper part of the float chamber, pasage 27, passage 26, etc. The structure which embraces the passages 23 and 24 at once begins to act as a venturi drawing in liquid fuel through the annular passage 30, the same being emulsified by the diffuser and being carried by the suction of the engine past the now partly open throttle valve to share with the mixture supplied by the priming nozzle in supplying the working mixtures The air orifice 29 is selected of such a size as to cause at this time a slight depression to exist in the atmosphere of the float chamber above the liquid level in said oat chamber. This causes a slight downward pressure upon the liquid at the submerged orifice 19 which is in a measure offset by a drop in static pressure equal to the column of liquid displaced fromv the diffuser at the moment when it first begins to act as a venturi. The commingling of the liquid fuel from the passage 30 with the air moving upwardly to the venturi causes an emulsiiication of the liquid fuel, decreases its density and at the same time increases its velocity. Since the vacuum formerly substantially confined to that part of the mixture passage engineward of the throttle valve is now shared by that part of the mixture passage on the opposite side of said throttle valve, the depression on the conduit l5 is increased, this serving to offset in some measure the rise of fuel in the idling nozzle, thus gradually tending to put the latter out of operation.

As the throttle valve is opened a little wider the liquid in the emulsifying unit continues to drop and the third phase in the operation of the carburetor begins. When the liquid fuel has descended just below the lower ends of the passages 32 the venturis represented by the passages 31 and 32 come into action, the liquid fuel being drawn in through the passages 40 and chamber 35 while the air is entrained from the chamber 34 coming in by way of the passages 32. The trunconic passages 3l thus become filled with emulsiiied carburant which now instead of the liquid fuel is drawn through the annular passage 30 and entrained in the air passing through the venturi constituted by the passages 23 and 24. A multiplication of the emulsiiication is thus in this manner accomplished, and while the depression in the upper part of the float chamber due to the increased demand for air is augmented yet at the same time its downward pull upon the liquid in the submerged orice 19 is for the most part offset by a drop in static pressure now equal to the column of liquid displaced from passages 31 and 32 when they begin to act as venturis.

Upon further opening of the throttle valve the fourth phase in the sequence of operations ape' pears, the liquid fuel being drawn out of the con.- duit 38 so that air now arrives at the lower ends of the vaporizers 36, the latter then giving a mixe ture of air and fuel which is dispersed laterally through the apertures 40 and thence into the venturis 31 where it is further emulsied. At this time there is produced in the oat chamber aV still greater depression due to the increased demand for air which can only come in by way of the fixed orifice 29, but this depression is in a measurev offset by a loss in the gravity head of liquid standing over the submerged orifice 19.

Now upon further opering of the throttle valve the fifth phase is reached. The previous phases have cleared all the passages of the device from the liquid fuel and its normal operation has now been attained. Due to the fact that the vacuum is substantially now the same on both sides of the throttle valve the pulling power of the conduit 11 upon the idling nozzle has become entirely neutralized and the idling nozzle is no longer in effect and since there are no more venturis to be uncovered, the static pressure upon the submerged jet 19 from this time forward remains constant. Up to this time, that is to say during the entire transition period from the idling position of the throttle valve to that position in which the idling nozzle has been put out of operation, the variation of static pressure on the submerged jet has substantially kept pace with the increasing counter-depression in the float chamber which is as it should be, since no force should be permitted to act during this period which might hold back or retard the velocity of the mixture fed to the engine. However, from the end of this transition period, the static pressure upon the submerged jet remaining constant, the depression in the float chamber will vary proportionately to the vacuum demand of the engine. In other words, as the engine runs faster and there is a demand for more mixture, the depression in the float chamber will increase, holding back the liquid at the orice 19 and thus slightly varying the proportion of the mixture in the direction of leanness. And when the engine runs slowly as when under load, the demand for mixture will be lessened, the depression in the float chamber correspondingly diminished and the liquid permitted to flow more freely through the submerged orice 19, slightly enriching the mixture.

It is to be understood that the maintenance of depression in the oat chamber has the important advantage of permitting a calibrated orice 19 of comparatively large diameter to be used, the flow of liquid therethrough being held back somewhat by the said depression. This tends to avoid stoppage of the orifice by foreign matter and it also, as stated in the general objects of the invention, lessens the skin friction of the liquid fuel with the walls of the orifice. Consequently the discharge capacity of the said orifice is very sensitive, and the liquid fuel can be rapidly discharged therethrough momentarily in response to a sudden pull upon thecarburetor by the engine. At the same time when the engine is running at normal uniform speeds, the depression will hold back the liquid fuel, economizing the consumption.

It is also to be understood that by building the emulsifyng unit as a series of venturis emerging one after another as the throttle valve opens, the density of the mixture is by stages diminished, its emulsication is perfected while its velocity is multiplied so that regardless of the engine demand the full weight of combustible mixture necessary to satisfy this demand is always available regardless of the speed of the throttle opening movement. It should be understood that the counter-depression in the float chamber is: without effect upon the velocity of the emulsied fuel, since the density of the gaseous mixture decreases with this counterdepression.

In the modification shown in Fig. 5 the series of vaporizing venturis 26 shown in Fig. 2 have been replaced by a single venturi 5l, apertures 52 communicating with the constricted portion of venturi 31 so as to facilitate the starting of said venturi. In other respects, this modification is substantially the same as that shown in Fig. 2, the diffuser herein shown being of the injecting type whereas the vaporizing diffuser 23 shown in Fig. 2 is an ordinary diffuser.

While I have in the above description endeavored to disclose what I believe to be an efficient and practical embodiment of my invention, it is to be understood that the invention is not limited by the specific details as shown but that it is subject to any and all structural variations which may express the invention and at the same time come within the scope of the appended claims.

What I claim is:

l. A carburetor comprising means forming a liquid fuel supply chamber, means forming a mixture chamber adapted to be connected to an engine intake, a chamber open to atmosphere,

Y a plurality of venturis arranged in a substantially '1 above it, except the uppermost one which is conupright series and located below the liquid level in the liquid fuel supply chamber, a lateral intake in the restricted portion of each venturi, the diverging portion of each venturi .being connected with the lateral intake of the one immediately nected to the mixture chamber, all the inlet ends of the venturis being connected to the chamber open to atmosphere, and a conduit for connecting the lateral intake of the lowerinost venturi with the liquid fuel supply chamber below the liquid level therein.

2. A. carburetor comprising means forminer a liquid fuel supply chamber having a restricted orifice open to atmosphere above the level of liquid in said chamber, means forming a mixture chamber adapted to be connected to an engine intake, plurality of venturis arranged in a substantially upright series and located below the liquid level in the liquid fuel supply chamber, a

lateral intake in the restricted portion of each venturi, the diverging portion of each venturi being connected with the lateral intake of the one immediately above it, except the uppermost one which is connected to the mixture chamber,

. all the inlet ends of the venturis being connected to the liquid fuel supply chamber above the level of liquid in said chamber, and a conduit for connesting the lateral intake of the lowermost venturi with the liquid fuel supply chamber below vthe liquid level therein.

. ture chamber adapted to be connected to an engine intake, mixture forming means comprising' a plurality of venturis arranged in a substantially upright series and being normally submerged in the liqui fuel at the time of starting of the engine, a conduit connecting the series of venturis with said liquid fuel supply chamber below the liquid level therein, a calibrated orifice in said conduit below the lowermost of the venturis, said venturis being in communication, between said calibrated orifice and said mixture chamber, with said liquid fuel supply chamber above the liquid level therein, the liquid fuel in which said series of venturis are normally submerged being subject to the suction of the engine intake whereby said liquid is depleted at the initial running of the engine causing progressive emergence of said venturis.

e. A carburetor comprising means constituting a liquid fuel supply chamber having a restricted orifice open to atmosphere above the level of liquid in said chamber, means forming a mixture chamber adaped to be connected to an engine intake, mixture forming means comprising a plurality of venturis arranged in a substantially upright manner and being normally submerged in the liquid fuel, at the time of starting of the engine, a lateral intake in the restricted portion of said venturi, the diverging portion of each venturi being connected with the lateral intake of the one immediately above except the uppermost one which is connected to the mixture chamber, all the inlet ends of the venturis being connected to the liquid fuel supply chamber above the level of liquid in said chamber, a conduit connecting the lateral intake of the lowermost of the venturis with the liquid fuel supply chamber below the liquid level therein, a calibrated orifice in said conduit, ther liquid fuel in which said venturis are normally submerged being subject to the suction of the engine intake whereby said liquid is depleted at the initial running of the engine causing progressive emergence of Vsaid venturis.

5. A carburetor comprising a liquid fuel supply chamber and a mixture chamber adapted to be connected to the engine intake, an emulsifying conduit including a series of venturis, said conduit establishing communication between said mixture chamber and said liquid fuel supply chamber below the liquid level of the latter, said emulsifying conduit including a series of venturis arranged at progressively higher levels and normally submerged in said liquid fuel at the time of starting of the engine so that they are inhibited as acting as venturis, said venturis being progressively emersible by the depression of the liquid in which'they are submerged through the initial suction of the engine at starting soV that they may progressively taire up and function as venturis, said venturis being connected to said liquid fuel supply chamber above the level of liquid in the latter, and means forming a re stricted orifice connecting said fuel supply chamber with atmosphere.

6. i carburetor comprising a liquid fuel sup ply chamber and a mixture chamber adapted t0 be connected to an engine intake, an emulsifying conduit establishing communication between said mixture chamber and said liquid fuel supply chamber below the liquid level of the latter, said emulsifying conduit including a series of venturis normally submerged in said liquid fuel at the time of starting of the engine so that they are inhibited as acting as venturis, said venturis ich isc

being so arranged as to progressively emerge by ll the depression of the liquid in which they are submerged through the initial suction of the engine at starting so that they may progressively take up and function as venturis, said venturis being connected. to said liquid fuel supply chamber above the level of liquid in the latter, and means forming a restricted orifice connecting said fuel supply chamber with atmosphere.

7. A carburetor comprising a liquid fuel supply chamber and a mixture chamber adapted to be connected to an engine intake, an einulsifying conduit establishing communication between said mixture chamber and said liquid fuel supply chamber below the liquid level in the latter, said emulsifying conduit including a plurality of groups of venturis disposed in parallel in each group, said groups being arranged at progressively higher levels and being connected to each other in series, said venturis being normally submerged in said liquid fuel at the time of starting of the engine so that they are inhibited as acting as venturis, and being connected to said liquid fuel supply chamber above the level of liquid in the latter, and means forming a restricted orifice connecting said fuel supply chamber with atmosphere.

8. A carburetor comprising means forming a liquid fuel supply chamber having a restricted orifice open to atmosphere above the level of liquid in said chamber, means forming a mixture chamber adapted to be connected to an engine intake, a plurality of venturis arranged in a substantially upright series and located below the liquid level in the fuel supply chamber, a lateral intake in the restricted portion of each of said venturis, the diverging portion of each venturi being connected with the lateral intake of the one immediately above it, except the uppermost one which is connected with the mixture chamber, an annular chamber surrounding said venturis and communicating on the one hand with the inlet ends of all these venturis and on the other end with the liquid fuel supply chamber above the level of liquid in said chamber, and

a conduit for connecting the lateral intake of the lowermost venturi with the fuel supply chamber below the level of the liquid therein.

9. A carburetor comprising means forming a liquid fuel supply chamber having a restricted orifice open to atmosphere above the level of liquid in said chamber, means forming a mixture chamber adapted to be connected to an engine intake, a plurality of venturis arranged in a substantially upright series and located below the liquid level in the fuel supply chamber, a lateral intake in the restricted portion of each of said venturis, the diverging portion of each venturi being connected with the lateral intake of the one immediately above it, except the uppermost one which is connected with the mixture chamber, an annular chamber surrounding said venturis and communicating on the one hand with the inlet ends of all these venturis and on the other hand with the liquid fuel supply chamber above the level of liquid in said chamber, a conduit provided with a calibrated orifice for establishing communication between the lowermost of these venturis and the liquid fuel supply chamber below the liquid level therein, said conduit including a vaporizing venturi the diverging portion of which opens into the lateral intake of the lowermost of the above mentioned venturis, and a passage for connecting said annular chamber with the converging part of said last mentioned venturi.

10. A carburetor adapted to be connected to an internal combustion engine comprising means forming a liquid fuel supply chamber, a plurality of mixture forming means arranged in series at different levels and being normally submerged in the liquid fuel at the time of starting of the engine, a conduit opening into said liquid fuel supply chamber below the liquid level in the latter, said conduit being provided with a calibrated orifice connecting it with the mixture forming means, a common chamber directly connected with all said mixture forming means and opening into the medium that supplies oxygen for the carbureted mixture.

11. A carburetor adapted to be connected to an internal combustion engine comprising means forming a liquid fuel supply chamber, a plurality of mixture forming means arranged in series at different levels and being normally submerged in the liquid fuel at the time of starting of the engine, a conduit opening into said liquid fuel supply chamber below the liquid level in the latter, said conduit being provided with a calibrated orifice for connecting it with the mixture forming means, a common chamber directly connected with all said mixture forming means and opening into the atmosphere.

12. A carburetor adapted to be connected to an internal combustion engine comprising means forming a liquid fuel supply chamber, a chamber open to the atmosphere, a plurality of funnel-shaped passages disposed at different levels, the wider end of each funnel-shaped passage being connected with the narrower part of the funnel-shaped passage located at the level immediately above it, conduits connecting in parallel the chamber open to the atmosphere to all the narrower ends of said funnel-shaped passages respectively, said conduits opening into the central Zones of said narrow ends respectively, excepted for the lowermost funnel-shaped passage for which the corresponding conduit opens into the peripheral zone of the narrow end of said passage, a calibrated hole located close to the narrow end of said lowermost passage, and a conduit connecting said calibrated hole with the liquid fuel supply chamber below the liquid level in the latter.

GEORGES FELIX BRUT. 

